The long term objective of this program is to investigate pathways of intermediary metabolism, energy production, and energy utilization by the lung parenchyma. Substrate utilization including both transcellular uptake and intracellular metabolism will be studied. This work will provide a framework for the investigation of the interactions of toxic agents with the pulmonary parenchyma and the metabolic defense mechanisms employed by the lung to protect against cellular damage. During the current year, we will utilize the isolated, perfused rat lung model to study 1) the energy requirements for uptake of alpha-methylglucoside (a non-metabolizable hexose) by the lung; 2) evaluate the sodium dependence of glucose uptake and metabolism; and 3) measure the substrate requirements for 5-hydroxytryptamine (serotonin) uptake by the lung. The goal is to determine the metabolic factors that affect active transport processes in the pulmonary parenchyma.